1. Field of the Disclosure
The present invention relates to a gas turbine engine having a fire wall and an actuatable device.
2. Description of the Related Art
It is common for a gas turbine engine to include a fire wall that is configured to provide a fire resistant barrier between a first zone and a second zone in the gas turbine engine, the second zone being hotter than the first zone when the gas turbine engine is in use.
It is also common for a gas turbine engine to include one or more actuatable devices configured to be actuated by a mechanical force. An example of such a device is a turbine case cooling valve.
In existing gas turbine engines, actuatable devices are usually configured to be actuated by hydraulic/pneumatic motive power, e.g. by using either fuel (typically sealed within a closed system of pipes and valves) or air to actuate the actuatable device.
The present inventors have observed that gas turbine engines are getting progressively hotter and that in very hot zones of a modern gas turbine engine, e.g. zones having a temperature of 300° C.-400° C. or higher, hydraulic motive power may not provide a reliable actuation mechanism for an actuatable device. In detail, the inventors have observed that using fuel as a source of hydraulic motive power at such temperatures can lead to the fuel heating up, breaking down and starting to coke, potentially leaving carbon deposits (e.g. in the closed system of pipes and valves). Similarly, the inventors have observed that using air as a source of pneumatic motive power at such temperatures can be problematic as air driven motors don't tend to work at such temperatures.
Such problems can be ameliorated by cooling the actuatable device, but the inventors have found that mechanisms for cooling an actuatable device tend to be complex, lossy, and only work up to certain temperatures.
The present invention has been devised in light of the above considerations.